Food Choice: Selection as a Construction of the Mind?
The act of making a conscious choice is a behavioral output. A fundamental linkage exists between this output and some form of input representing that about which one is reaching a decision. When a choice is made to purchase one car over the others in a dealer’s lot, for example, the basis for this decision is the summation of knowledge about cars that the buyer has received in his car-buying experience through different modalities—visual, auditory, kinesthetic, social perception. When one chooses to study neurobiology, one makes a choice based on what one has heard about the field, the visual attraction of fMRI images and pictures of the brain, and past experience in associated fields. Not surprisingly, food choice is made through a similarly multi-modal progression of decision-making, largely dictated by neural processes. The choice to consume a particular food item is made based on a wealth of visual, olfactory and gustatory information, as well as the persistent firing and communication of interneurons, which bring to the table past experiences from the hippocampal memory center, emotional triggers for food desires from the limbic system, evolutionary adaptive information, and implicitly conditioned responses.
The visual modality is one that affords the brain the ability to glean information in many dimensions. In looking at a pizza pie and attempting the selection of a piece to eat, one can receive visual input that is translated by internuerons into salient information about each slice’s size, depth of crust, amount of cheese, brightness of sauce, temperature (based on steam rising from its surface), and any number of other traits of the pizza slice. All of these pieces of visual information are then analyzed by the brain so that a decision can be reached. While the pathway by which this decision-making process occurs is not easily explained, there may be an adaptive, evolutionary force behind the actions of the brain leading to the behavior of choice. A recent study by Toepel, et al. employed multiple hemodynamic imaging methods and Visual Evoked Potentials to record neural activation in response to food images depicting high-fat and low-fat foods (2009). The literature provides evidence that within the prefrontal region of the brain and the orbitofrontal cortex (OFC), cortical and sub-cortical networks react to visual stimuli in the form of food and simple images of food, in addition to previously determined reaction to gustatory and olfactory food stimuli (de Araujo, 2003).
The neural response to food stimuli—in the visual, gustatory and olfactory modalities—occur within the OFC, a region of association cortex that is highly relevant in the psychological processes of learning and extinction (Shepherd 2006). Research has established that much of the taste and olfactory systems are located in the prefrontal cortex and both project to, and converge on the OFC, where images of food led to neural activity in the study by de Araujo, et al. (2003). The location of the olfaction and gestation centers in the brain were discovered through the experimental recording of neural response to an olfactory stimulus alone, a gustatory stimulus alone, and then the response to having both stimuli present at once (Small 2005). If these were two separate processes, it would be expected that the response to both stimuli together would be equal to the sum of the two stimuli alone. In fact, the response when both stimuli were presented together was much enhanced from the sum of the two independent responses, so we can define olfaction and gestation as inherently interconnected (Small 2005).
The previously mentioned study by Toepel examined the ability of the brain to implicitly judge food items based on their potential to provide energy, fat and general sustenance. Knowing that images of food elicit responses in the OFC, the study presented subjects with pictures of low and high fat food items and found, by examining their unintentionally grouped VEPs in response to the image and the ‘food or non-food’ classifying task with which they were presented, that subjects experience the two groups differently, a phenomenon that likely leads people to make decisions about eating from the two groups in divergent ways. (Toepel 2009). It has been suggested that this discrepancy between VEPs of low and high fat food items supports the vastly researched evolutionary principle that animals, primates in particular, have natural identification abilities toward food, which allow us to respond negatively to, for example, extreme bitterness—a possible sign of toxicity—and remain healthy so as to protect our group and promulgate the species (Shepherd 2006).
Our natural instinct toward certain foods can provide an evolutionary explanation for the fascination toward brightly colored foods and foods that are sugary and filled with quick-delivering energy in the form of polysaccharides. Similarly, the primate tendency to lose desire for a given food item after having satisfied a prior craving for it allows for more variety of diet and thus a greater likelihood that nutrients and essential amino acids, those which cannot be synthesized by the body, will be consumed (Shepherd 2006). Further, neuronal activation in response to taste and nasal stimuli, based on single-cell recordings in monkeys, are highly tied to the environment into which the monkey is placed and the presence of learning and reward tasks. Conditioning provides a mechanism by which food preferences can be developed by means of implicitly learned negative response to foods that, in the past, have led to unpleasant physiological or mental reactions or events (Shepherd 2006). In addition, eating “activates neural substrates in a similar manner to drugs of abuse,” activating GABA and dopamine neurotransmitters, emphasizing a calming effect and encouraging the desire for continued eating and the attainment of more nutrients (Gibson 2006).
From the literature it is clear that there are an astounding number of neural input, activation and output forces that could be driving food choice. It is interesting, bearing in mind this ample selection of neurological and physiological implicit motivations toward choice, to consider the function of the brain in making a choice. Not only does the brain make a selection based on one or a combination of these myriad directions from which to reach a decision, but it must make the choice as to which of these neural and sensory inputs it will adhere. The framework depicted by an Emily Dickenson poem, that all human experiences, and the environmental “realities” by which we are surrounded, are constructions of the mind, can be applied here (Dickinson 2009). According to this way of viewing science and the world, the many influences on food choice are constructions of the mind and thus, the process of making a choice is not neurological; no more is it an active process of selection. In the sense that the choice being made is not the choice of food item, but rather the choice of mental process, decision making evolves from the simple selection of the construction, which will act to determine the food choice itself. The final output of a decision-making process is the selection of a particular ‘construction of the mind’ reality. The path leading up to this selection, however, is the brains choice of which construction of the mind will have precedent and will dictate the output selection which we see enacted as behavior.
If it is to be assumed that the process of coming to a decision is analogous to the process of the brain selecting a construction of the mind as the factor to which it will hold in its choice of food, we must expand further. How can the brain, clearly a part of our ‘reality’ and thus subject to Dickenson’s rule, be a construction of the mind, if its main role in decision making is the process by which another construction of the mind is chosen?
De Araujo, I.E., Rolls, E.T., Kringelbach, M.L., McGlone, F., Phillips, N., 2003. Taste-olfactory convergence, and the representation of the pleasantness of flavour in the human brain. European Journal of Neuroscience. 18(7), 2059-2068.
Dickinson, E. “The Brain-is Wider Than the Sky.” Retrieved February 23, 2009, from Neurobiology and Behavior, Spring, 2009 Web site: http://serendip.brynmawr.edu/exchange/courses/bio202/s09/home
Gibson, E.L., 2006. Emotional influences on food choice: Sensory, physiological and psychological pathways. Physiology and Behavior. 89, 53-61.
Shepherd, G.M., 2006. Smell images and the flavour system in the human brain. Nature. 444(16), 316-321.
Toepel, U., Knebel, J-F., Hudry, J., le Coutre, J., Murray, M.M., 2009. The brain tracks the energetic value in food images. NeuroImage. 44, 967-974.